Internal combustion engine

ABSTRACT

A four-cycle internal combustion engine having a cylinder provided with a head end and a crankcase end with a fuel inlet valve in the head end and an exhaust outlet opening in the cylinder wall in position to be passed by the piston and spaced from the head end of the cylinder a distance equal to a major portion of the stroke of the piston in the cylinder, the disclosure also including an exhaust valve in the head end of the cylinder communicating with an exhaust gas recycling conduit adapted to recycle exhaust gases into an intake manifold, and a flow valve intercommunicating with said exhaust gas recycling conduit and said intake manifold for coordinating or modulating flow of recycled exhaust gases into the intake manifold in relation to fuel being conducted to said fuel inlet valve in the head end of said cylinder. Also disclosed is an engine similar to the foregoing wherein the first mentioned exhaust outlet opening is provided with an exhaust valve held closed in spring loaded outlet with the opening and so adjusted as to provide an exhaust outflow to atmosphere according to combustion pressure in the cylinder when the piston passes to a position near the end of its power stroke. The disclosure also relating to a novel method of operating a four-cycle internal combustion engine and exhausting efficiently burned products of combustion to the atmosphere and recycling most inefficiently burned products of combustion to the intake for mixture with incoming fuel for reintroduction into the combjustion chambers of the engine.

United States Patent 1191 Villella l l INTERNAL COMBUSTION ENGINE TonyR. Villella, 3106 Hewitt Ave. Everett. Wash. 98201 [22] Filed: Apr. 23,I973 [211 Appl. No.: 353,341

Related U.S. Application Data [76] Inventor:

[52] U.S. Cl. 123/119 A; 123/75 C [51] Int. Cl. F02m 25/06 [58] Field ofSearch 123/75 C, 119 A [56] References Cited UNITED STATES PATENTS 1,052340 2/1913 Holst 123/75 C 1.579.425 4/1926 Wilson 75/C 1,933,619 11/1933Edwards 1 123/119 A 2.239.262 4/1941 Violet 123/75 C X 2.701.556 2/1955Woerner e 123/119 A 3.470.857 111/1969 Stivender 123/119 A 3.579.9815/1971 Gau i 123/119 A 3.583375 6/1971 Pischingerm. 123/119 A 3.682.1518/1972 Tatsutomi 123/119 A Primary Examiner-Wendell E. Burns [57]ABSTRACT A four-cycle internal combustion engine having a cyl- 1 1 Apr.8, 1975 inder provided with a head end and a crankcase end with a fuelinlet valve in the head end and an exhaust outlet opening in thecylinder wall in position to be passed by the piston and spaced from thehead end of the cylinder a distance equal to a major portion of thestroke of the piston in the cylinder, the disclosure also including anexhaust valve in the head end of the cylinder communicating with anexhaust gas recycling conduit adapted to recycle exhaust gases into anintake manifold. and a flow valve intercommunicating with said exhaustgas recycling conduit and said intake manifold for coordinating ormodulating flow of recy cled exhaust gases into the intake manifold inrelation to fuel being conducted to said fuel inlet valve in the headend of said cylinder. Also disclosed is an engine similar to theforegoing wherein the first mentioned exhaust outlet opening is providedwith an exhaust valve held closed in spring loaded outlet with theopening and so adjusted as to provide an exhaust outflow to atmosphereaccording to combustion pressure in the cylinder when the piston passesto a position near the end of its power stroke.

The disclosure also relating to a novel method of operating a four-cycleinternal combustion engine and exhausting efficiently burned products ofcombustion to the atmosphere and recycling most inefficiently burnedproducts of combustion to the intake for mixture with incoming fuel forreintroduction into the combjustion chambers of the engine.

7 Claims, 13 Drawing Figures PATENTED 9 5 Q 87 91 SriiET 10? 8 y FIG.3.

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INTERNAL COMBUSTION ENGINE This application is a continuation in part ofmy copending application for Internal Combustion Engine, Ser. No.322,761, filed Jan. ll, 1973 now abandoned.

PRIOR ART The following U.S. Patent Nos. are noted:

Wilson l,579,425 Violet 2,239,262 Woerner 2,70l,556 Gau 3,579,98lPischinger 3,583,375 Edwards l,933,6l9 Stivender 3,470,857.

BACKGROUND OF THE INVENTION Conventional four-cycle engines comprisepistons movable in cylinders, and these pistons traverse four strokecycles in the cylinder for each ignition and power stroke therein andexhaust and intake valves operate in the head end of the respectivecylinder for conventional four-stroke inlet and exhaust cycles relativeto the movement of the piston in the cylinder. Conventional four-cycleengines, depending upon piston and combustion chamber shape, as well asthe placement of the valves and the spark plugs, all operate efficientlyto a degree with relation to the combustion of fuel and expeciallyhydrocarbons. as well as other gaseous products. It has been necessaryto operate such engines with a substantially rich fuel mixture whereinan excessive amount of hydrocarbon fuel relative to oxygen, is present,so that exhaust gases from such engines usually include a substantialportion of hydrocarbons and unburned gaseous products. Thus,conventional fourcycle engines have been operated with a seriousresultant emission contaminating effect on the atmosphere. The necessityfor operating conventional four-cycle en gines with a rich fuel mixturehas been occasioned by a requirement that the valves in the engine donot become overheated and oxidized rapidly. It is well known thatconventional four-cycle engines operating on a lean fuel mixture, wherethere is sufficient oxygen or an overage of oxygen for the consumptionof the hydrocarbon fuels, deteriorate rapidly due to overheating of theexhaust valves and oxidation thereof. While a lean fuel mixture and hightemperatures cause exhaust valves to deteriorate rapidly, theseconditions also cause nitric oxide to be produced at temperatures inexcess of 2,750 degrees Fahrenheit or thereabouts. On the other handhydrocarbons and carbon monoxides require substantial temperature forefficient burning thereof and fuel that is completely consumed producesonly harmless carbon dioxide and accordingly it is well known that it isdifficult to compromise between the problems related to the emission ofhydrocarbons and carbon monoxide and also nitric oxide. Accordingly, ithas been necessary to apply various accessories and equipment to theinduction and exhaust systems of these engines in order to reduce theforegoing undesirable gaseous emission from the exhaust of thereof.

SUMMARY OF THE INVENTION The present invention related to a four-cycleinternal combustion engine, wherein combustion chambers and cylindersare provided with a head end and with pistons reciprocally mountedtherein, and wherein intake and exhaust valves are communicating withthe head end of the cylinder and wherein a stratifying exhause port andvalve are disposed in the side wall of the cylinder a substantialdistance from the head end of the cylinder so that strata of exhaustgases may be exhausted from areas adjacent the top of the piston as thepiston passes the respective exhaust port in the side wall of thecylinder.

The aforementioned exhaust valve in the head end of 5 the combustionchamber and the cylinder communicates through an exhaust gas recyclingconduit with the intake manifold of the engine which communicates withthe aforementioned inlet valve at the head end of the cylinder, and flowcontrol valve means controls the flow of the recycled exhaust gasespassing through the recycling conduit to the fuel inlet manifold of theinvention so as to coordinate the amount of exhaust gas recycled inrelation to the amount of fuel mixture conducted through the intakemanifold and into the combustion chamber through the intake valve at thehead end of the cylinder and combustion chamber.

The invention also comprises an exhaust valve in the aforementioned portin the side wall of the cylinder for the prevention of raw fuel fromexcaping from the cylinder during the start of the compression stroke.

The invention also relates to the stratification of exhaust gases in acombustion chamber and cylinder, wherein flame travel moves directlyfrom the spark plug in the head end of the cylinder to the hot surfaceof the piston and whereby combustion is most efficient at the hotsurface of the piston due to the short time interval and due to theefficient atomization of the fuel adjacent the piston, all of whichcauses efficient combustion at the surface ofthe piston, whereupon thepiston, in moving to the end of its power stroke longitudinally of thecylinder, passes an exhaust port in the side wall of the cylinder andthe most efficiently burned products of combustion at the surface of thepiston are first exhausted through said last mentioned exhaust port inthe side wall of the cylinder and whereupon the relatively poorly orunburned gases remain in the cylinder at the head end thereof to berecycled through an exhaust valve and back through a recycling conduitto the fuel inlet manifold which communicates with the intake valveinthe head end of the cylinder and combustion chamber of the engine.

The invention comprises a novel method for operating a four-cycleinternal combustion engine wherein a multi-cylinder internal combustionengine is operated sequently moving a plurality of pistons in respectivecylinders and a rich recycling fuel mixture is introduced into the headend of the cylinders through air intake means and this rich fuel mixtureis fired at the hot surfaces of the pistons in the cylinders whichcauses the pistons to be driven away from the head ends of the cylindersnear the ends of the power stroke in the cylinders, then the mostefficiently burned gases are exhausted to atmosphere from the surfacesof the pistons at the positions thereof near the ends of the powerstrokes of the pistons leaving the most inefficiently burned products ofcombustion in the head ends of the cylinders. then the pistons are movedtoward the head ends of said cylinders and the most inefficiently burnedproducts of combustion are exhausted into the intake means of the engineand mixed with a fresh fuel mixture, such that said inefficiently burnedproducts thus mixed produce a rich recycling mixture whereupon therecycling mixture is introduced into the head ends of the cylinders andfired therein.

Accordingly, it is an object of the invention to provide a novelfour-cycle internal combustion engine with means for stratifyingproducts of combustion in the combustion chambers and cylinders of theengine so as to exhaust the most efficiently combusted gases to theatmosphere and to recycle the relatively unburned gases for subsequentcombustion in the combustion chambers of the engine.

Another object of the invention is to provide a novel four-cycle enginein which the most efficiently combusted fuel products adjacent thesurface of a hot piston are efficiently stratified in the combustionchamber and cylinder and are allowed to escape through a port in theside wall of the cylinder in spaced relation to the head end thereofwhen the piston reaches a position corresponding to a major portion ofits power stroke in the respective cylinder.

Another object of the invention is to provide a novel method ashereinbefore set forth. Further objects and advantages of the inventionmay be apparent from the following specification, appended claims andaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a sectional view of afour-cycle internal combustion engine in accordance with the presentinvention. showing parts and portions in elevation to facilitate theillustration;

FIG. 2 is a fragmentary sectional view similar to FIG. 1 but showing thepiston in top dead center position preliminary to an intake strokethereof;

FIG. 3 is a figure similar to FIG. 2, showing a progression of theintake stroke with the piston moving away from the head end of thecylinder and with the inlet valve open admitting a fuel mixture to thecombustion chamber;

FIG. 4 is a view similar to FIG. 3, showing a completion of the intakestroke with the combustion chamber filled with a fuel mixture and withthe intake valve still open but ready to close;

FIG. 5 is a sectional view similar to FIG. 4 but showing a successivecompression stroke of the piston to ward the head end of the cylinderand showing the in take and exhaust valves in the head end of thecylinder closed;

FIG. 6 is another sectional view similar to FIG. 5, showing the fuelmixture compressed in the cylinder and with the piston at a pointwherein ignition is accomplished by a spark plug in the head end of thecylinder combustion chamber;

FIG. 7 is a sectional view similar to FIG. 6, showing a power stroke ofthe piston in the cylinder resulting from ignition of the fuel mixturein the combustion chamber by the spark plug and showing the flame traveland relative stratification of products of combustion where combustionis most efficiently attained at the surface of the piston due to itsrelatively higher temperature than that in the surrounding combustionchamber area;

FIG. 8 is a view similar to FIG. 7, showing the most efficiently burnedgases escaping through a port in the side wall of the cylinder as thepiston reaches a position in its power stroke which is equal to a majorportion of the stroke. and also showing a stratification between themost efficiently burned gases passing out the exhaust port in the sidewall of the cylinder and the relatively unburned products of combustionin the combustion chamber end of the cylinder;

FIG. 9 is a view similar to FIG. 8 showing a successive movement of thepiston toward the combustion chamher head end of the cylinder andshowing an exhaust valve in the head end of the cylinder open to allowrecycling of the relatively unburned products of combustion through arecycling conduit to the intake manifold of the engine;

FIG. 10 is a sectional view similar to FIG. 9, showing a continuedexhaust gas recycling operation through the exhaust valve in the headend of the cylinder;

FIG. 11 shows a subsequent intake stroke of the piston with the intakevalve open and the recycling of the previously recycled exhaust gasesmixed with fresh fuel from the intake manifold of the engine;

FIG. 12 is a view similar to FIG. 1 but showing a modification of theinvention wherein an exhaust port in the side wall of the cylindersubstantially spaced from the head end thereof is open to the atmosphereand not controlled by an exhaust valve; and

FIG. 13 is a view similar to FIG. 1 showing a modified form of theinvention wherein a spring loaded exhaust valve is disposed to be openedby power stroke gas pressures at a position near the end of the pistonpower stroke in a respective cylinder of the engine.

DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. I of thedrawings, a four-cycle engine, in accordance with the invention, isprovided with a water cooled block 20 having a cylinder head 22 thereon;the block 20 is a multi-cylinder engine having several cylinder bores 24with respective pistons 26 reciprocally mounted therein and connected toconventional connecting rods 28 by suitable wrist pins 30, theconnecting rods 28 being connected with a conventional crankshaft.

The cylinder bore 24 is provided with a head end substantially enclosedby the cylinder head 22 and wherein receptive intake and exhaust valves32 and 34 are reciprocally operable in the conventional manner by meansof respective rocker arms 36 and 38 actuated by respective push rods 40and 42 which are engaged with conventional lifter mechanisms 44 and 46,respectively. These lifter mechanisms 44 and 46 are reciprocallyoperated by a conventional rotary cam shaft 48 adapted for timedoperation of the valves in accordance with the disclosures of operationin FIGS. 2 to 11, inclusive, of the drawings, as will be hereinafterdescribed in detail.

The intake valve 32 communicates with an intake manifold 50 whichcommunicates with a plurality of said intake valves 32 at the head endof respective cylinders 24.

Communicating with the exhaust valve 34 is an exhaust gas recyclingconduit 52 which communicates with the intake manifold 50 through a flowcontrol valve 54 which is operated in cooperative relation with thethrottle of a carburetor 56 which communicates with the intake manifold50.

Each cylinder 24 is provided with an exhaust port 58 which is spaced aconsiderable distance from the head end of 60 of each cylinder 24 andthis exhaust port 58 communicates with atmosphere and is disposed to bebypassed by the head end 62 of each respective piston 26 as the pistoncycles to its farthest position from the cylinder head 22 and therespective combustion cham ber therein.

Communicating with the exhaust port 58 is a poppet valve 64 having astem 66 reciprocally mounted in a valve guard 68. A spring loaded lifterengaging plate 70 is mounted on the stem 66 adjacent to a keeper 72holding a compression spring 74 which is abutted at 76 to the valve case78.

The spring 74 tends to hold the valve 64 on a seat 80 surrounding theport 58 while the lifter engaging plate 70 is adapted to be lifted topull the valve head off the seat 80 by means of bifurcated valve lifter82 pivoted on a rocker shaft 84, the lifter 82 having a cam followerportion 86 operable by appropriate lobes 88 on the cam 48. The lobes 88being timed relative to the stroke of the respective piston 26 to openthe valve 64 appropriately in accordance with the disclosures ofoperation in FIGS. 2 to 11 of the drawings, as will be hereinafterdescribed in detail.

As shown in FIG. 2, the piston 26 is in top dead center position withboth intake and exhaust valves 32 and 34 closed, and with the valve 64closed against its seat 80. In this position, the piston is at itsfarthest stroke toward the head end of the cylinder 24 and immediatelythereafter the piston moves in the direction as shown in FIG. 3 of thedrawings, wherein the intake valve 32 is opened by the cam 48 so that afuel mixture may flow around the valve 32 and into the combustionchamber at the head end 60 of the cylinder 24 as the piston moves in thedirection of an arrow A in FIG. 3 of the drawings.

As shown in FIG. 4 of the drawings, the piston subsequently passes fromthe position shown in FIG. 3 to the furthermost position in its strokeso that the combustion chamber above the piston is filled with a fuelmixture designated 90 in FIG. 4 of the drawings. At this time the intakevalve 32 closes to the position shown in FIG. 5 of the drawings, all thewhile the exhaust valve 64 remains on its seat 80. The piston 26, asshown in FIG. 5, then moves in the direction of an arrow B toward thehead end 60 of the cylinder 24, compressing the fuel mixture 90 whileboth intake and exhaust valves 32 and 34 are in closed position.

Following the stroke position shown in FIG. 5, the piston progresses tothe position shown in FIG. 6, wherein the fuel mixture 90 is fullycompressed and ready for ignition by a spark plug 91 in the cylinderhead 22. Following the stroke position of FIG. 6, the piston as shown inFIG. 7 is forced in a direction of an arrow C away from the cylinderhead 22 by combustion of the fuel mixture in the upper part of thecylinder 24, while both intake and exhaust valves 32 and 34 remainclosed.

It will be seen that the spark plug 91, when fired, causes flame totravel directly to the upper surface or head end 62 of the piston 26,due to the fact that the piston at its surface 62 is generally at ahigher temperature than other areas of the engine due to the fact thatthese other areas are water cooled, as for example, the cylinder head 22and block surrounding the cylinders 24 are all water cooled and heatmust flow from the piston 26 to these areas; consequently, thetemperature on the surface 62 of the piston forms a relatively hotcombustion chamber surface which tends to provide most favorable burningconditions for the fuel mixture 90 compressed in the position as shownin FIG. 6, and subsequently ignited and expanded as shown in FIG. 7.

It will be appreciated by those skilled in the art that since thesurface 62 of the piston 26 is at higher temperature than the remainingcombustion chamber areas, generally speaking, the fuel mixture on thesurface 62 of the piston will be burned at the highest temperature andwill be most efficiently burned.

When the piston 26 is driven by combustion pressure of the fuel mixture90 under combustion, as shown in FIG. 7, the piston moves in thedirection of the arrow C and at this time the cam 48 opens the exhaustvalve 64 from its seat 80 around the port 58, and as the head end 62 ofthe piston 26 moves to a position as shown in FIG. 8 of the drawings,this end 62 of the piston 26 passes the port 58 with the valve 64 openand allows the most completely combusted gases to excape through theport 58 to atmosphere from the head end 62 of the piston 26. It will beseen from FIGS. 7 and 8 that portions of the gases designated 92 and 94at opposite sides of the spark plug 91 are not burned as efficiently asthe gases near the hot surface 62 of the piston 26. Accordingly, thesegaseous portions 92 and 94 in the head end of the cylinder, even thoughthey expand toward the piston, do not pass outwardly through the exhaustport 58, all as shown in FIGS. 8 and 9 of the drawings.

The piston 26, shown in FIG. 8 of the drawings, is in its fartheststroke position from the head end of the cylinder 24, and the pistonthen progresses in the direction of the arrow B toward the head end ofthe cylinder 24, and at this time the valve 64 is moving toward closedposition with respect to the seat surrounding the port 58.

As the piston 26 moves in the direction of the arrow B in FIG. 9 theexhaust valve 34 is opened to allow substantially unburned hydrocarbons95, from the gaseous portions 92 and 94, to pass into the recyclingconduit 52 and through the valve 54 to the intake manifold 50, all asindicated by a broken line 96 in FIG. 9 of the drawings.

Accordingly, the most efficiently burned products of combustion from thesurface 62 of the piston pass outwardly through the exhaust port 58 tothe atmosphere, and the relatively inefficiently combusted gasescontaining hydrocarbons remain in the head end 60 of the cylinder andare exhausted through the recycling conduit S2 to the intake manifold50.

During this recycling of inefficiently combusted fuel products to theintake manifold 50, the relatively unburned hydrocarbons are mixed withfresh fuel mixtures passing through the manifold 50 and are then readyfor induction into the head end 60 of other ones of the cylinders 24through their respective intake valves 32, as shown in FIG. 11 of thedrawings. At this time, the respective piston 26 is moving in thedirection of the arrow C in FIG. 11 of the drawings, and fresh fuelmixed with unburned products of combustion are induced into thecombustion chamber as the piston 26 moves in the cylinder 24 to create apartial vacuum therein. Subsequently, the mixture of fresh fuel andunburned hydrocarbons is combusted in a manner as hereinbefore describedrelative to FIGS. 6 and 7 of the drawings.

In the modification as shown in FIG. 12 of the drawings, the port 58 isnot provided with a valve 64, and accordingly, this combination ofelements may be arranged to operate in a similar manner to that hereinbefore described when certain proportions of the engine. including boreand stroke, and the disposition of the exhaust port is such thatmovement of the piston toward the head end of the cylinder after thefuel intake stroke.

will not cause substantial losses of the raw fuel mixture through theport 58. This intake and compression function of the structure, as shownin FIG. 12 of the drawings, will be dependent upon proportions of theengine and the relative disposition of the port 58 and the stroke of thepiston 26 so as to permit efficient exhaustion of most efficientlyburned gases and yet to prevent the loss of raw fuel mixture from theport 58 after the intake stroke and during the compression strokeprevious to ingition of the fuel charge, generally as indicated in FIGS.6 and 7 of the drawings.

As shown in FIG. 13, a modified form of the engine of the inventioncomprises the poppet valve 64 and spring 74 tending to hold the poppetvalve 64 closed against the seat 80 and an adjustable plug 59 is screwthreaded in the housing 61 so as to adjust compressive force of thespring 74 and thereby adjusting the force of the head of the valve 64against the seat 80 so that the valve can be adjusted to respond tonominal pressure in the cylinder 24 when the piston 26 reaches aposition near the end of its power stroke wherein the upper surface 62of the piston bypasses the port 58. As hereinbefore described, the valve64 only serves to prevent a fuel mixture from excaping through the port58 following the intake stroke and during compression of the fuel in thecylinder preliminary to the firing stroke or power stroke. Accordinglyit will be appreciated then that the pressure of the valve 60 on theseat 80 may be light and that the spring 74 may be adjusted to tune theexhaust to desired low pressure forces required for opening the valveand yet to maintain the valve closed during the initial compressionstages of the fresh fuel charge in the cylinder 24 by the piston 26.

It will be appreciated that the spring loaded valve 64 as shown in FIG.13, is not limited by any cam operation and is so adjusted that it willopen readily under engine load, but when the carburetor throttle valveis closed on normal vehicle deceleration, the exhaust valve 64 remainsclosed and does not allow any substantial amount of fuel mixture orproducts to escape to the atmosphere through the port 58. Further, itwill be appreciated that when the engine is under load and high powerstroke pressures in the cylinder 24, that the valve 64 will operaterapidly without any cam limitations and thereby obviate the usual valveerosion problems attendant to the positive operation of valves by meansof cams or the like.

It will be appreciated that the spring loaded valve 64, as shown in FIG.13, when properly loaded by the spring 74, simplifies emission controlnormally attendant to the deceleration of an engine where the throttleof the carburetor 56 is closed and the engine is coasting down hill, forexample.

Additionally, it will be understood that the valve 54 provides forcontinuous recycling when the engine is operating under power but may beclosed when the throttle of the carburetor is closed so that the inefficiently burned gaseous products will remain in the con duit 52 until thecarburetor throttle is again opened for admitting a fuel mixture to therespective engine combustion chambers.

The valve 54 will be controlled in cooperation with the usual controlvalve of the carburetor 56 so as to provide for sufficient negativepressures at the carburetor for proper fuel mixture induction and alsoto provide for the recycling of an appropriate amount of theinefficiently burned products through the conduit 52 back to the engineintake manifold 50 for recycling and reintroduction of the recyclingthrough the valve 32 and into the appropriate combustion chamber 60.

The method of the invention comprises a method for operating amulti-cylinder four-cycle internal combustion engine wherein the engineis provided with a plurality of cylinders having sequentially movablepistons which are moved in the usual sequence relative to each other forintake, compression, power, and exhaust strokes. The method comprisesthe introduction of a rich recycling fuel mixture into the head end ofthe respective engine cylinders through an intake means and firing ofthe rich recycling fuel mixture at the hot surfaces of the pistons inthe cylinders and driving the pistons away from the head ends of thecylinders to positions near the ends of the power strokes in thecylinders, then exhausting to atmosphere, the most efficiently burnedproducts of combustion from the surfaces of the pistons at saidpositions near the ends of the power stroke of the pistons while leavingthe most inefficiently burned products of combustion in the head ends ofthe cylinders, then moving the pistons toward said head ends of saidcylinders and exhausting the most inefficiently burned products ofcombustion from the cylinders into said intake means of said engine andmixing a fresh fuel mixture with said inefficiently burned productstherein to produce said rich recycling mixture; then introducing saidrich recycling fuel mixture into the head ends of said cylinders andfiring said rich recycling fuel mixture therein.

It will be obvious to those skilled in the art that variousmodifications of the invention may be resorted to without departing fromthe spirit thereof.

I claim:

1. In a four-cycle internal combustion engine, the combination of: acylinder having a head end and a crankcase end; a piston reciprocallymounted in said cylinder; a fuel inlet valve communicating with saidhead end of said cylinder; said cylinder having an exhaust outletopening in the sidewall thereof; said exhaust outlet openingcommunicating with atmosphere and being spaced from said head end ofsaid cylinder a distance equal to a major portion of the stroke of saidpiston in said cylinder; an exhaust outlet valve disposed incommunication with said head end of said cylinder; a recycling conduitmeans communicating between and with said exhaust outlet valve and saidfuel inlet valve.

2. The invention as defined in claim 1, wherein: an exhaust outlet valveis disposed to control flow of exhaust gases through said exhaust outletopening in the sidewall of said cylinder.

3. The invention as defined in claim 1, wherein: rotary cam means isprovided for opening said fuel mixture inlet valve once during each fourstrokes of said piston in said cylinder.

4. The invention as defined in claim 2, wherein: rotary cam means isprovided for opening said exhaust outlet valve once during each fourstrokes of said piston in said cylinder.

5. The invention as defined in claim 2, wherein: ro' tary cam means isprovided for opening said fuel inlet valve and said exhaust outlet valveonce during each four strokes of said piston in said cylinder; saidrotary cam means being timed to operate said fuel inlet valve at onedown stroke cycle of said piston in said cylinder and adapted foroperating said exhaust outlet valve at 7. The invention as defined inclaim 6, wherein: a second exhaust outlet valve is disposed to controlflow of exhaust gases through said exhaust outlet opening in thesidewall of said cylinder and cam means adapted to open said secondexhaust valve when fuel is ignited at the head end of said cylinder andwhen said piston moves during the power stroke in said cylinder touncover said exhaust outlet opening.

1. In a four-cycle internal combustion engine, the combination of: acylinder having a head end and a crankcase end; a piston reciprocallymounted in said cylinder; a fuel inlet valve communicating with saidhead end of said cylinder; said cylinder having an exhaust outletopening in the sidewall thereof; said exhaust outlet openingcommunicating with atmosphere and being spaced from said head end ofsaid cylinder a distance equal to a major portion of the stroke of saidpiston in said cylinder; an exhaust outlet valve disposed incommunication with said head end of said cylinder; a recycling conduitmeans communicating between and with said exhaust outlet valve and saidfuel inlet valve.
 2. The invention as defined in claim 1, wherein: anexhaust outlet valve is disposed to control flow of exhaust gasesthrough said exhaust outlet opening in the sidewall of said cylinder. 3.The invention as defined in claim 1, wherein: rotary cam means isprovided for opening said fuel mixture inlet valve once during each fourstrokes of said piston in said cylinder.
 4. The invention as defined inclaim 2, wherein: rotary cam means is provided for opening said exhaustoutlet valve once during each four strokes of said piston in saidcylinder.
 5. The invention as defined in claim 2, wherein: rotary cammeans is provided for opening said fuel inlet valve and said exhaustoutlet valve once during each four strokes of said piston in saidcylinder; said rotary cam means being timed to operate said fuel inletvalve at one down stroke cycle of said piston in said cylinder andadapted for operating said exhaust outlet valve at an appropriate strokeof said piston when moving toward said head end of said cylinder.
 6. Theinvention as defined in claim 1, wherein: an intake manifoldcommunicates with said fuel mixture inlet valve; said recycling conduitmeans communicating with said intake manifold; a flow control valve insaid recycling conduit to control flow of gases therethrough in relationto the flow of a fuel mixture into said combustion chamber through saidintake manifold and said fuel inlet valve.
 7. The invention as definedin claim 6, wherein: a second exhaust outlet valve is disposed tocontrol flow of exhaust gases through said exhaust outlet opening in thesidewall of said cylinder and cam means adapted to open said secondexhaust valve when fuel is ignited at the head end of said cylinder andwhen said piston moves during the power stroke in said cylinder touncover said exhaust outlet opening.